Kindergarteners need access to blocks as thinking tools to develop, model, test, and articulate their mathematical ideas. In the current educational landscape, resources such as blocks are being pushed to the side and being replaced by procedural worksheets and academic "seat time" in order to address standards. Mathematics research provides a solid basis for advocating for hands on resources to explore geometry and number concepts. Through the use of blocks in standards based mathematical tasks, students have the opportunity to develop important mathematical concepts and reasoning strategies. Kindergarten teachers' instructional actions can be grounded in history, research, personal wisdom, and professional knowledge regarding what is appropriate and meaningful for their students in learning mathematics with thinking tools such as blocks.